The Philly Cheesesteak: What is it and where's the best?

Well, I’m not from Philly, but I’ve eaten cheesesteaks there. Some were excellent, many were not.

The cheesesteaks at 2 current Seattle eateries and one closed one were better than all but a few I’ve had in Philly:

Tat’s Deli: http://www.tatsdeli.com/default.asp
Colozzi’s: https://www.facebook.com/calozzisgeorgetown
Philly Fevre: now closed

I get the whole “pride of place” thing, but saying you can’t get an excellent cheesesteak anywhere but Philly is, well, a little silly.